1. Field of the Invention
The present invention relates to ultrasonic scanning systems and, in particular, to an ultrasonic scanning transducer for examining an object.
2. Description of the Prior Art
Ultrasonic scanning systems are being used presently to examine objects of various natures to determine their characteristics. Physicians and medical technicians are using ultrasonic scanning systems to detect abnormalities in the human body and to examine human fetuses in the mothers' uteri. Further, ultrasonic scanning systems are being used to discover the existence and location of inanimate objects and materials and to inspect metals and metal objects for flaws.
Basically, the ultrasonic scanning transducer of an ultrasonic scanning system gather data relating to the nature of the object by directing a series of ultrasonic waves into an object and receiving and processing the series of echoes generated when the waves strike acoustical interfaces within the object. Examples of an acoustical interface include the interface between the human organ and the tissue surrounding the organ and the interface between a piece of metal and a flaw located within it. Generally, the echoes generated at the acoustical interfaces are converted to electrical signals by the transducer. Those signals are processed and transmitted to the scanning system for further processing and display, commonly on a cathode-ray tube. By properly timing the generation of ultrasonic waves and the processing of returning echoes, the transducer can produce electrical signals containing information relating to the existence of acoustical interfaces in the object and the nature of the material surrounding those interfaces. By properly scanning the object and displaying on the cathode-ray tube the electrical signals produced by the transducer, the examiner can actually see an image of a portion of the object under examination, including acoustical interfaces located within it. An example of such an ultrasonic scanning system and transducer therefor can be found in U.S. Pat. No. 4,092,867 issued to the applicant herein.
Several factors determine the level of desirability of an ultrasonic transducer. The first factor is the resolution of the scanning system. If the resolution is not adequate, the image displayed on the cathode-ray tube will not accurately depict the object. The second factor is the number of gray levels available with the display. The usefullness of the displayed image increases with the number of gray levels with which the displayed image is constructed. The third factor is the ease with which the system can be used. The size, shape and weight of the transducer itself determine in part the ease with which the entire scanning system can be used. The fourth factor is the cost of the transducer.